I think your definition of meta-data is too narrow. It's not just keywords. Excuse me if I state the obvious, but with something like a web page access, the m

I think your definition of meta-data is too narrow. It's not just keywords. Excuse me if I state the obvious, but with something like a web page access, the meta data will be in part: your internet address, what time you accessed it, the referring url etc. A phone call's meta data could include the length of the call, which phone the call was made on, which mast was used etc. Meta data is additional data about the data isn't it? One assumes that you could then make telling deductions from that meta data. Like a persons movements (acquired from phone, financial and internet records). You can also draw a lot about their character: their interests, their political views, their cicles etc. The meta data is very revealing in itself.